[Scip] Finding out what presolve does

[Timo Berthold]

Hi Victor,

you can look at the statistics (type "display statistics" in the
interactive shell or call SCIPprintStatistics(scip) when using SCIP as a
library).
This way you can see, which of the presolvers, propagators or constraint
handlers performed the reductions.
Then, add a #define SCIP_DEBUG as first line of the corresponding *.c file
in src/scip (e.g. cons_linear.c or presol_probing.c)
Recompile and run again. You will get heaps of information now.
Of course, looking into the code of the corresponding plugin and the
respective chapter in Tobias Achterbergs PhD thesis should help the
investigation.

Good luck, :-)
Timo

)> I have some interesting combinatorial problems.  I find that Scip (and
> Cplex) does a lot of massaging in presolve, such as bounds reduction.  Is
> there some way that I can get Scip to give me a trace of its reasoning?  I
> think that looking that will help me understand some of the combinatorial
> structure of the problem.
>
> Victor
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